make happy in one's pants

1. To suddenly discover that one, under circumstances of excitement or happiness, that one has in fact ejaculated.

2. Goes the same for any type of substance which has been released into the underpants.

Mommy...I made happy in my pants again...
What have i told you about playing on the tyre swing?

1. Wow! A Butterfly!
It's enough to make happy in one's pants

2. You make one happy in one's pants!